General Information
Type IS-1
Function Experimental Fighter
Year 1939
Crew 1
Powerplant
Type M-63 (ASh-63)
Power at 4500m 900hp
Size
Length 6.79m
Height 2.74m
Wingspan 8.6m
Wing area (biplane) 20.83m2
Wing area (monoplane) 13.0m2
Weights and loads
Empty 1400kg
Loaded 2300kg
Wing load (takeoff) 111
Wing load (cruise) 177
Power load (kg/hp) 2.56
Speed (monoplane)
at 0m 400km/h
at 4900m 453km/h
Speed (biplane)
Landing 115km/h
Maneuverability
Turn time ?sec
Roll
Takeoff 250m 10sec
Range
Practical 600km
Ceiling
Ceiling 8800m
Climb
5000m 8.2min
Payload
Fuel ?kg
Guns
4*7.62mm ShKAS (1000 rounds)

IS-1, V.V.Nikitin, V.V.Shevchenko

33k b/w IS-1 photo from 'Soviet Combat Aircraft of the Second World War'
Courtesy of Thomas Heinz

The 'IS' series stands for Istrebitel Skladnoj (Folding Fighter) - unique compromise between biplane and monoplane fighters: it was both. The lower wing could be retracted upwards, flush with the forward fuselage and the upper wing, while the wheels retracted into the lower wing surfaces.

This concept may be considered one of the first (and successful!) to implement variable geometry wing. 'IS' in its biplane configuration had excellent takeoff/landing characteristics and increased payload, while switching to monoplane scheme in flight allowed reach higher speed and range.

26k b/w drawing by I.G.Soultanov from "History of aircraft construction in the USSR", Vol.2 p.101

V.V.Nikitin started working on the plane in 1938, but real boost to the project came from pilot/engineer V.V.Shevchenko. As a result, new design bureau was organized in 1939 - OKB-30. V.V.Shevchenko became Designer General, and V.V.Nikitin - his first deputy.

Fuselage for new aircraft was borrowed from the N.N.Polikarpov I-153 fighter. Upper wing was replaced by one with larger span but narrower chord. Lower wing had two folding points: one at the root and another at about mid-span on each side. Hydraulic jacks with indigenous system of levers provided perfectly synchronous operation on both sides. 'Hamilton' 3-blade propeller (d=2.8m) was fitted.

IS-1 was completed in late 1939 and flown soon after by LII test-pilot G.M.Shijanov (factory trials). The first in-flight translation from monoplane to biplane and back again was in June of 1940, proving that the concept was workable. Nonetheless, IS-1 was found inferior against conventional monoplane fighters (MiG-3, LaGG-2, Yak-1) and was not permitted to State Trials.

But the concept was not yet completely abandoned.

Drawing (24k) provided by Dean McGinnes

46k drawing by I.G.Soultanov from "History of aircraft construction in the USSR", Vol.2 p.101, used as a background for this page;
PredecessorsModifications
None
IS-2
ReferencesLinks
  • "History of aircraft construction in the USSR", Vol.2 p.101-103;
  • "Russian Civil and Military aircraft 1884~1969", p.114;
  • IS-1
  • IS-2 profile in Polsky
  • IS-1, Shevchenko-Nikitin
  • Special thanks to Dean McGinnes for providing drawings and historical info.

    Created November 26, 1996
    Modified January 31, 2000
    with help of Thomas Heinz
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